Automated processing of digital images is often based on the color values of individual pixels in a digital image. However, digital images, such as pictures taken by a digital camera, often capture scenes that include direct lit areas and also areas that are in shadow. As will be recognized by those skilled in the art, the areas that are in shadow are represented, in the digital image, by pixels that have less intensity, or otherwise different color values. Often, automated processing of digital images cannot distinguish between a darker object and an object that is simply in shadow. Consequently, to provide for more accurate automated processing of digital images it is desirable to be able to identify those regions, in a digital image, that are in shadow and, thereby, account for such shadows in the automated processing.
Traditional mechanisms for identifying those regions, in a digital image, that are in shadow were based on the color values of the individual pixels in the digital image. More specifically, those pixels with darker colors were determined to be in shadow, while those pixels with lighter colors were determined to be directly lit objects. As is known by those skilled in the art, however, such traditional mechanisms had a difficult time distinguishing between dark objects that were directly lit and other objects, whether dark or not, that were simply in shadow.
Another traditional mechanism for identifying those regions, in a digital image, that are in shadow was based on the ability to digitally capture, not only the visible light, but near infrared (NIR) light as well. Subsequently, those areas of the scene that were in shadow could be identified based on a comparison between the visible light and the NIR light. Obviously, such a mechanism could not be implemented if the digital imaging equipment did not comprise the ability to capture NIR light.